Insights into the enhancement mechanism coupled with adapted adsorption behavior from mineralogical aspects in bioleaching of copper-bearing sulfide ore by Acidithiobacillus sp.

Abstract

The enhancement mechanism of adapted adsorption behavior in the bioleaching of copper-bearing sulfide ore by Acidithiobacillus sp. was systematically investigated from a mineralogical viewpoint and compared to adsorption-deficient (DF) and adsorption-unadapted (UA) systems. With the assistance of the adapted adsorption behavior, both iron and sulfur metabolism was enhanced, which was proven by a series analysis of key chemical parameters, including scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM analysis revealed smaller jarosite and S⁰ granules as well as more potential adsorption sites on the ore’s surface, thus indicating a stronger “contact” mechanism. XRD analysis showed that more chemical derivatives were generated owing to active iron/sulfur metabolism. Additionally, the attached and free biomasses of A. ferrooxidans and A. thiooxidans were increased by 33.3–58.9% and 25.0–33.9%, respectively. Moreover, the final concentration of the extracted copper ions was improved by 22.8% (A. ferrooxidans) and 28.9% (A. thiooxidans). All results proved that the adsorption behavior coupled to the attached cells was greatly stimulated and accelerated by the adapted evolution and further contributed to a higher bioleaching efficiency. The adapted method and its mechanism will be useful to further guide similar bioleaching processes in the near future.